Effect of variation of environmental conditions on the microbial communities of deep-sea vent chimneys, cultured in a bioreactor

Abstract

Both cultivation and molecular techniques were used to investigate the microbial diversity and dynamic of a deep-sea vent chimney. The enrichment cultures performed in a gas-lift bioreactor were inoculated with a black smoker chimney sample collected on TAG site on the mid-Atlantic ridge. To mimic as close as possible environmental conditions, the cultures were performed in oligotrophic medium with nitrogen, hydrogen and carbon dioxide (N(2)/H(2)/CO(2)) gas sweeping. Also, the temperature was first settled at a temperature of 85 degrees C and colloidal sulphur was added. Then, the temperature was lowered to 60 degrees C and sulphur was omitted. Archaeal and bacterial diversity was studied in both culture and natural samples. Through 16S rRNA gene sequences analysis of the enrichment cultures microorganisms affiliated to Archeoglobales, Thermococcales were detected in both conditions while, Deferribacterales and Thermales were detected only at 65 degrees C in the absence of sulphur. Single-stranded conformational polymorphism and quantitative PCR permit to study the microbial community dynamic during the two enrichment cultures. The effect of environmental changes (modification of culture conditions), i.e. temperature, medium composition, electron donors and acceptors availability were shown to affect the microbial community in culture, as this would happen in their environment. The effect of environmental changes, i.e. temperature and medium composition was shown to affect the microbial community in culture, as this could happen in their environment. The modification of culture conditions, such as temperature, organic matter concentration, electron donors and acceptors availability allowed to enrich different population of prokaryotes inhabiting hydrothermal chimneys.

Biogeochemical insights into microbe–mineral–fluid interactions in hydrothermal chimneys using enrichment culture

“…(Postec et al 2005), or in the ferric iron reduction with Geoglobus sp. (Byrne et al 2009a). However, no evidences were reported for Fe or S oxidation metabolic pathways, and for the simultaneous presence of sulfur, sulfate and iron reducers.…”

“…and Deferribacter sp.) occurred at the same time (Byrne et al 2009a), while for the other, that iron reduction, sulfur reduction and sulfate reduction took place simultaneously (Postec et al 2007).…”

“…(Byrne et al 2009a)] and Marinitoga sp. (Postec et al 2005), or in the ferric iron reduction with Geoglobus sp.…”

“…The enrichment culture was carried out during 23 days (36 h in batch mode and 21 days in continuous mode culture), at 85 °C in an 850 mL glass gas-lift bioreactor as previously described (Godfroy et al 2006;Byrne et al 2009a;Postec et al 2007). Briefly this equipment allows to perform Tivey and Delaney 1986;Tivey et al 1999;Kerr 1997) cultures in controlled temperature and pH conditions and under continuous gas sweeping.…”

“…In addition, the cultivation system allowed maintaining constant N 2 /CO 2 /H 2 atmosphere through continuous gas sparging (Postec et al 2005(Postec et al , 2007Byrne et al 2009a). Here, we choose to maintain the enrichment culture at 85 °C to cultivate hyperthermophilic organisms.…”